Coated items and manufacturing thereof

ABSTRACT

A method for manufacturing a coated item 10 in a chemical deposition reactor and a coated item produced by said method are provided. The method comprises deposition of a first coating on a first surface of the item 10, and/or deposition of a second coating on a second surface of said item.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of copending application Ser. No.16/894,049, filed on Jun. 5, 2020, which claims priority under 35 U.S.C.§ 119(e) to U.S. Provisional Application No. 62/858,069, filed on Jun.6, 2019, all of which are hereby expressly incorporated by referenceinto the present application.

FIELD OF THE INVENTION

The present invention generally relates to manufacturing of coated itemsby chemical deposition methods. In particular, the invention concernsregion-specific deposition of coatings onto interlaced substrates bymethods of chemical deposition in vapour phase.

BACKGROUND OF THE INVENTION

Chemical deposition methods, such as Chemical Vapor Deposition (CVD) andAtomic Layer Deposition (ALD), are extensively described in the art. ALDtechnology generally regarded as a subclass of CVD processes has provedan efficient tool for manufacturing high-quality conformal coatings onthree-dimensional substrate structures.

ALD is based on alternating self-saturative surface reactions, whereindifferent reactants (precursors) provided as molecular compounds orelements in a nonreactive (inert) gaseous carrier are sequentiallypulsed into a reaction space accommodating a substrate. Deposition of areactant is followed by purging the substrate by inert gas. ConventionalALD cycle (a deposition cycle) proceeds in two half-reactions (pulsefirst precursor—purge; pulse second precursor—purge), whereby a layer ofmaterial (a deposition layer) is formed in a self-limiting(self-saturating) manner, typically being 0.05-0.2 nm thick. The cycleis repeated as many times as required for obtaining a film with apredetermined thickness. Typical substrate exposure time for eachprecursor ranges within 0.01-1 seconds. Common precursors include metaloxides, elemental metals, metal nitrides and metal sulfides.

ALD offers significant benefits in view of capability of the method togenerate coatings on complex, multi-element 3D structures or scaffoldstructure, since precursor molecules distributed in gaseous media resideat all accessible (not-masked) surfaces forming conformal coatings.

However, the same functionality constitutes a significant drawback whenapplied to formation of region-specific coating layers. For example,traditional chemical deposition methods do not allow producingregion-specific (selective) coatings on interlaced structures.Nevertheless, a need for such coatings exists in medical field, forexample, in where it would be desirable to obtain implantableintravascular stents (provided as expandable mesh structures) withdifferent material properties for inner and outer surfaces. TraditionalALD methods would inherently produce conformal coatings across allsurfaces of such items; thus preventing a manufacturer from producingmedical devices with desired properties.

In this regard, an update in the field of vapour-deposition basedmethods, such as atomic layer deposition technology, is still desired,in view of addressing challenges associated with the application of saidmethods in manufacturing of three-dimensional interlaced structures withregion-specific coatings.

SUMMARY

An objective of the present invention is to solve or to at leastalleviate each of the problems arising from the limitations anddisadvantages of the related art. The objective is achieved by variousembodiments of a method for manufacturing coated interlaced substratesand coated interlaced items produced by said method.

Thereby, in an aspect of the invention, a coated item is provided,according to what is defined in independent claim 1. In embodiment, thecoated item comprises a coating formed by a method for manufacturing acoated interlaced substrate in a chemical deposition reactor, the methodcomprising:

obtaining a chemical deposition reactor with a reaction space formed bya reaction chamber and configured to receive, at least in part, asubstrate holder made of a fluid-permeable material, onto which aninterlaced substrate is mounted such, that a first surface of thesubstrate faces the reaction space, and a second surface of thesubstrate is placed against the substrate holder, and in a number ofdeposition cycles, forming a first coating on the first surface andforming a second coating on the second surface, wherein, each depositioncycle comprises delivering, with a flow of fluid, precursor chemicalinto the reaction space such, that delivery of at least one precursorchemical into the reaction space occurs via said fluid-permeablematerial.

In embodiment, the deposition cycle comprises delivering at least twopredetermined precursor chemicals into the reaction space, whereby adeposition layer is produced across the first surface of the substrateand/or across the second surface of said substrate.

In embodiment, a first predetermined precursor chemical is deliveredinto the reaction space via the reaction chamber and a secondpredetermined precursor chemical, is delivered into the reaction spacevia the fluid-permeable substrate holder.

In embodiment, the precursor chemicals are delivered into the reactionspace in sequential, temporally separated pulses, optionally alternatedby purging the reaction space with inert fluid.

In embodiment, delivery of any one of the precursor chemicals into thereaction space is accompanied by generating a counter flow of inertfluid in a direction essentially opposite to the direction of deliveryof precursor chemicals into the reaction space.

In embodiment, any one of the first coating and the second coating areformed by the at least one deposition layer deposited across the firstsurface of the substrate and/or across the second surface of saidsubstrate.

In embodiment, the deposition layers forming the first coating differfrom the deposition layers forming the second coating by virtue of atleast composition thereof.

In embodiment, formation of the coating on the first and/or the secondsurfaces is regulated by adjusting pressure of fluid flowing into thereaction space via the reaction chamber and/or via the fluid-permeablesubstrate holder.

In embodiment, the substrate holder is made of a fluid-permeablematerial selected from the group consisting of porous metal, porousceramics and porous polymer.

In embodiment, the substrate holder has an essentially hollow interior,into which said at least one precursor chemical is received. Inembodiment, the substrate holder is an essentially tubular structure.

In embodiment, the interlaced substrate is an essentially tubularstructure formed by a mesh or a web.

In embodiment, the interlaced substrate is an implantable medicaldevice, such as a stent or a catheter, or forms a part of such device.

In embodiment, the coating is deposited onto the interlaced substratewith Atomic Layer Deposition (ALD).

In another aspect, a coated implantable medical device is providedaccording to what is defined in the independent claim 15.

In embodiment, said coated implantable medical device is configured asan interlaced structure, comprising a first coating on a first surfaceand/or a second coating on a second surface, wherein the first coatingand the second coating differ from one another by virtue of at leastcomposition thereof.

In embodiment, the first surface is an exterior surface of theimplantable medical device and the second surface is an interiorsurface, respectively.

In embodiment, the coated implantable medical device is a stent, such asan expandable stent, or a catheter.

The utility of the present invention arises from a variety of reasonsdepending on each particular embodiment thereof. Deposition layers(atomic layers or films) deposited by ALD methods are pinhole-free andfully conformal, therefore, the ALD technology has a high potential inmanufacturing of high-quality coatings required for variousapplications, in particular, medical applications. The method disclosedhereby thus allows for rendering selective surfaces of an exemplaryinterlaced structure (a scaffold-like structure) with different surfacechemistries and regions-specific properties, such as ability toattract/repel water, ability to bind other molecules, and the like.Hence, by the method disclosed hereby, particular surface regions (e.g.internal and external surfaces) of the interlaced structures, such as,such as implantable (intra)vascular stents or catheters, can be renderedwith distinct physicochemical and/or biological functions.

The method further allows for selective preventing or sustainingmaterial deposition, such as ALD deposition, for example, on any one ofthe surfaces (inner or outer) of the exemplary essentially tubularmedical device, such as a stent or a catheter.

In addition to coating of the aforesaid implantable items, the methoddisclosed hereby is fully applicable for depositing region-specificcoatings on any essentially interlaced structures with or withoutessentially tubular configuration. Hence, coating of essentially planarinterlaced structures is not excluded.

In the present disclosure, materials with a layer thickness below 1micrometer (μm) are referred to as “thin films”.

In the context of present disclosure, the term ALD comprises allapplicable ALD based techniques and any equivalent or closely relatedtechnologies, such as, for example the following ALD sub-types:plasma-assisted ALD, PEALD (Plasma Enhanced Atomic Layer Deposition) andphoton-enhanced Atomic Layer Deposition (known also as photo-ALD orflash enhanced ALD).

The expression “a number of” refers herein to any positive integerstarting from one (1), e.g. to one, two, or three; whereas theexpression “a plurality of” refers herein to any positive integerstarting from two (2), e.g. to two, three, or four.

The terms “first” and “second” are not intended to denote any order,quantity, or importance, but rather are used to merely distinguish oneelement from another.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 shows an interlaced substrate 10 mounted on a substrate holder100.

FIGS. 2 and 3 show a method for manufacturing a coated interlacedsubstrate 10, according to the embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 2 and 3 illustrate a method for manufacturing a coated interlacedsubstrate in a chemical deposition reactor.

The interlaced substrate 10 to be coated comprises a first surface 10Aand a second surface 10B. Coating process is implemented in an exemplarychemical deposition reactor comprising a reaction chamber 101 with areaction space (deposition space) established by an interior of saidreaction chamber 101.

The reactor is configured to exploit principles of vapor-depositionbased techniques, such as Atomic Layer Deposition (ALD).

The basics of ALD growth mechanism are known to a skilled person. ALD isa chemical deposition method based on sequential introduction of atleast two reactive precursor species to at least one substrate. It is tobe understood, however, that one of these reactive precursors can besubstituted by energy when using, for example, photon-enhanced ALD orplasma-assisted ALD, for example PEALD, leading to single precursor ALDprocesses. For example, deposition of a pure element, such as metal,requires only one precursor. Binary compounds, such as oxides can becreated with one precursor chemical when the precursor chemical containsboth of the elements of the binary material to be deposited. Thin filmsgrown by ALD are dense, pinhole free and have uniform thickness. In someinstances, Chemical Vapour Deposition (CVD) may be utilized.

The at least one substrate is typically exposed to temporally separatedprecursor pulses in a reaction vessel to deposit material on thesubstrate surfaces by sequential self-saturating surface reactions. Inthe context of this application, the term ALD comprises all applicableALD based techniques and any equivalent or closely related technologies,such as, for example the following ALD sub-types: MLD (Molecular LayerDeposition), plasma-assisted ALD, PEALD (Plasma Enhanced Atomic LayerDeposition) and photon-enhanced Atomic Layer Deposition (known also asphoto-ALD or flash enhanced ALD).

A basic ALD deposition cycle, resulting in deposition of a depositionlayer (atomic layer), consists of four sequential steps: pulse A, purgeA, pulse B and purge B. Pulse A consists of a first precursor fluid andpulse B of another precursor fluid. Inactive gas and a vacuum pump aretypically used for purging gaseous reaction by-products and the residualreactant molecules from the reaction space during purge A and purge B. Adeposition sequence comprises at least one deposition cycle. Depositioncycles are repeated until the deposition sequence has produced a thinfilm or coating of desired thickness. Deposition cycles can also beeither simpler or more complex. For example, the cycles can includethree or more reactant vapor pulses separated by purging steps, orcertain purge steps can be omitted. On the other hand, photo-enhancedALD has a variety of options, such as only one active precursor, withvarious options for purging. All these deposition cycles form a timeddeposition sequence that is controlled by a logic unit or amicroprocessor.

In terms of an overall implementation, the deposition reactor may bebased on an ALD installation described in the U.S. Pat. No. 8,211,235(Lindfors), for example, or on the installation trademarked as PicosunR-200 Advanced ALD system available from Picosun Oy, Finland.Nevertheless, the features underlying a concept of the present inventioncan be incorporated into any other chemical deposition reactor embodiedas an ALD, MLD or CVD device, for example, or any subtype thereof.

The reaction chamber can be configured as an open-top vessel sealed witha lid (not shown). Such type of a reactor has an essentially circularlayout when viewed from the top. In some instances, the reaction chambercan be configured as a vessel loadable from side or from the bottom (notshown). In such configurations the lid is configured as a hatch disposedlaterally (within a sidewall) or at the bottom of the reactor vessel.Such type of reaction chambers may have a crossflow blown from the side,for example.

The reactor further comprises a number of appliances configured tomediate a flow of fluids into the reaction space 101 (the reactionchamber). Mentioned appliances are provided as a number of intake lines(hereafter, feedlines) and associated switching and/or regulating valves(not shown).

The reactor further comprises an evacuation line (not shown) fordischarging an exhaust flow, such as excess carrier, precursor andreaction products, out of the reaction chamber. The evacuation lineconstitutes a fore-line for an evacuation pump unit and it may comprise,in some configurations, a closing valve, preferably upstream the pumpunit. It is preferred that withdrawal of fluidic substance from thereaction chamber is implemented in an uninterrupted manner, whereby thepump unit, preferably configured as a vacuum pump, removes fluidicsubstance from the reaction chamber continuously during the entiredeposition process.

The interlaced substrate 10 is mounted onto a substrate holder 100, suchthat its first surface 10A faces the reaction space 101 and its secondsurface 10B is placed against the substrate holder 100.

The interlaced substrate 10 can be provided in the form of a mesh or aweb, such as a wire mesh, for example, optionally an expandable wiremesh.

The interlaced substrate 10 can be configured as an essentially tubular,pipe-like structure (see FIG. 1 ). Alternatively, the interlacedsubstrate 10 can be configured as an essentially flat, planar structure(not shown).

In embodiments, the interlaced substrate 10 is an implantable medicaldevice, such as a stent or a catheter. An exemplary configurationincludes an expandable, mesh-wire type vascular stent. Alternatively,the substrate 10 forms at least a part of said medical device.

In some configurations, the substrate holder 100 can be disposedessentially between the reaction chamber and any feedline (or a relatedappliance for directing precursor fluids into the reaction space). Insome instances, the substrate holder 100 is received, at least partly,into the reaction chamber. For example, the substrate holder can beplaced between the feedline and the reaction chamber such, that only aportion of said substrate holder (with the substrate 10 mounted thereto)is received into the reaction space, unless partial coating (e.g.lengthwise) of the substrate item is desired.

The substrate holder 100 can be further positioned, at least partly,inside a feedline or form, at least partly, a part of the feedline.

The substrate holder 100 is preferably made of an essentiallyfluid-permeable material, such as porous material, that enablesunhindered fluid flow therethrough. The substrate holder can thus form afluid-permeable passageway for precursor fluids entering the reactionspace. In some configurations, the substrate holder 100 is positionedsuch that fluids, flowing via the feedline(s) into the reaction space101, can enter said reaction space only by penetrating through thefluid-permeable material forming said holder of made of.

In some configurations (FIG. 1 ) the substrate holder 100 is anessentially tubular structure, onto which the interlaced substrate item10 can be mounted. The substrate holder 100 can be provided as anessentially solid (without internal apertures and/or channels) piecemade of fluid-permeable material. In some instances, it is preferredthat the holder 100 has an essentially hollow interior 102, in the formof a through-channel or a blind-end channel, for example.

In terms of its structure, the substrate holder 100 includes all kindsof essentially tubular, channel-like shapes that enable uniform flowacross their entire surfaces to attain the effect described hereinbelow.

The fluid-permeable material that constitutes the substrate holder 100can be represented by any one of the porous metal, porous ceramics orporous polymer, including silicone polymer. Other materials, such asporous composites and semiconductor materials (e.g. silicon) are notexcluded.

The substrate holder 100 can be further configured as a fork- orrake-like arrangement with a common base portion and a number ofprotrusions/protruding “fingers” onto which the substrate items 10 to becoated can be mounted (not shown). The base portion of such holder canbe made hollow and connected to a feedline or feedlines. The substrateholder for essentially flat, planar substrate items 10 can beimplemented based on a similar principle.

Additionally or alternatively, a number of substrate holders can beplaced into the reaction space 101.

In exemplary configurations, position of the substrate holder 100 withregard to the reaction chamber is such, that fluids directed into thereactive space 101 via the feedlines, for example, enter the reactionspace 101 via the fluid-permeable material.

Precursor fluid(s) is/are delivered inside the reaction space 101 bymeans of at least one feedline connectable to a container with aprecursor chemical.

To incorporate a number of individual substrate holders configured asfluid-permeable passageways, the reactor can comprise two, three or morefeedlines and a corresponding number of inlets. The reactor can compriseas many feedlines and associated inlets as considered feasible in termsof the deposition process and the apparatus design. One or more suchfeedlines can be connected directly to the substrate holder 100, to feedfluids there into.

In other configurations (in particular, in case of providing support formultiple substrate items 10; the rake-like arrangement), the substrateholder 100 can be placed inside the reaction chamber and connected tothe feedline(s) via its base portion.

Precursor chemicals are delivered into the reaction space 101 (viafeedlines) in a fluidic form. Precursor fluid delivered into thereaction space 101 is a gaseous substance comprising a predeterminedprecursor chemical A, B, B1, B2 (FIGS. 2, 3 ) carried by an inertcarrier. Whether the precursor is inherently provided in a gaseous form(e.g. NH₃, or O₂), dilution of such precursor with a carrier fluid maynot be required. Carrier fluid without the precursor chemical isindicated on FIGS. 2 and 3 by a character X.

Precursor chemicals are supplied into the reaction space from a supplysource or sources configured as containers, cartridges or a pipingsystem, for example (not shown). Each source preferably contains apredetermined precursor species A, B, B1, B2 provided as a chemicalcompound, a molecule, or an element. Each source is equipped with atleast one valve, provided as a manual closing valve, for example. Avariety of precursor chemicals required for deposition reaction(s), suchas ALD reaction(s), can be directed into the reaction space via a singlefeedline.

As mentioned above, precursor(s) can be provided in a gaseous form, suchas ammonia gas (NH₃) or oxygen gas (O₂), which may be modified at leastpartly to ozone (O₃) by an appropriate equipment, such as ozonegenerator (not shown). Additionally or alternatively, precursor(s) canbe provided in liquid or solid forms and vaporized prior to beingadmixed to the inert carrier.

Inert carrier X is a fluid, preferably gas, such as nitrogen (N₂), argon(Ar) or any other suitable gaseous medium that possesses essentiallyzero reactivity towards the precursors (reactants) and the reactionproducts. Inert carrier gas X is supplied from a separate source orsources (not shown).

The method disclosed hereby involves a number of deposition cycles,whereupon a first coating 1 is formed on the first surface 10A of thesubstrate and a second coating 2 is formed on the second surface 10B ofthe substrate (FIG. 3 ). During each deposition cycle, a number ofprecursor species are delivered into the reaction space resulting information of a deposition layer (an atomic layer), whereas production ofa coating 10A, 10B comprises depositing at least one, but typically morethan one deposition layer onto the substrate.

Each deposition cycle comprises delivering, with a flow of fluid,precursor chemicals into the reaction space 101 such, that delivery ofat least one precursor chemical into the reaction space 101 occurs viathe fluid-permeable material the substrate holder 100 is made of.

In embodiments, the deposition cycle comprises delivering at least twopredetermined precursor chemicals into the reaction space 101, whereby adeposition layer produced across the first surface 10A of the substrate10 and/or across the second surface 10B of said substrate.

Delivery of said at least two predetermined precursor chemicals isimplemented such that the first precursor chemical enters into thereaction space 101 via the reaction chamber (and a correspondingfeedline or feedlines, not shown), whereas the second precursor chemicalis directed into said reaction space 101 via the fluid-permeablesubstrate holder 100.

In embodiments, the deposition layers forming the first coating 1 differfrom the deposition layers forming the second coating 2 by virtue of atleast composition thereof, thus rendering the coated surfaces bydistinct surface chemistry. Other differentiating factors include, butare not limited to thickness and density of the final coating films,ability to attract and repel water molecules, as well as any otherchemical, physical- and/or biological property. Biological propertiescan include e.g. specific responses at a substrate— (biological) hostinterface, an ability of not having toxic or injurious effects onbiological systems, an ability to act as a suitable implantablematerial, an antimicrobial activity, and the like.

Fluidic flow through the essentially fluid-permeable material 100 can becontrolled by pressure difference generated across said material withthe evacuation pump and a number of regulating devices, such as switchvalves equipped with mass-flow controller(s) and/or gas flow meter(s),for example. Other control means include conventional appliances, suchas gas- and pressure sensors. The chemical deposition reactoradvantageously comprises an (automated) control system, implemented as acomputer unit, for example, and comprising at least one processor and amemory with an appropriate computer program or software.

By adjusting pressure difference generated across the essentiallyfluid-permeable substrate walls, formation of coating(s) 1, 2 withvarying composition and/or other properties can, in turn, be regulated.By regulating pressure difference, velocity of fluid flowing into thereaction space 101 via the reaction chamber (P_(out)) and via thefluid-permeable substrate holder (P_(in)) can be adjusted.

In embodiments, the coating(s) 1, 2 is/are deposited onto the interlacedsubstrate 10 with Atomic Layer Deposition (ALD).

Various ways of implementing the method shall be presented hereinbelowin a number of non-limiting examples.

Example 1. Installation and Assembly

An interlaced substrate 10 is obtained in the form of a stent deviceprovided in the form of an essentially tubular, scaffold mesh-typestructure. The stent can be configured as an implantable device, such asa self-expandable metallic stent. The stent has an outer surface 10A andan inner surface 10B. The stent 10 is positioned onto/around thefluid-permeable substrate holder 100 such, that its first surface 10Afaces the reaction space 101 and its second surface is placed againstthe substrate holder (FIG. 1 ).

The fluid-permeable substrate holder is made of a porous material thatenables unrestricted flow of fluids, such as gaseous media,therethrough. Hereby, the fluid-permeable substrate holder 100 can beconfigured as an essentially tubular inlet comprising the hollowinterior 102.

The substrate holder 100 with the stent 10 mounted thereon, as shown onFIG. 1 , is placed into the reaction space 101 formed by a reactionchamber of an exemplary ALD reactor. By the way of example, theinstallation R-200 Advanced ALD system available from Picosun Oy,Finland, can be utilized. The holder 100 is connected to a feedline orfeedlines (the feedline is not shown). When fluid is directed into thereaction chamber via the feedline(s) connected to the holder 100, fluidenters the reaction space 101 essentially through the fluid-permeablematerial said holder is made of.

The reactor further comprises at least one feedline through whichfluid(s) are delivered into the reaction space. Such feedline(s) is/arenot connected to the substrate holder 100.

Fluid flow into the reaction space 101 through the feedline(s), ontowhich the substrate holder 100 is mounted or incorporated, and throughthe interior 102 of said substrate holder is further referred to as aflow from the “inside” (“in”), whereas fluid flow directly entering thereaction space (via feedline(s) provided, but not shown, with the holder100) is referred to as a flow from the “outside” (“out”).

The flow from the interior side 102 of the tubular substrate holder 100to the reaction space 101 through the essentially fluid-permeablematerial (100) can be controlled by adjusting pressure difference(P_(in)/P_(out)) generated across the essentially fluid-permeablesubstrate walls. By regulating pressure difference, velocity of fluidsflowing across the fluid-permeable wall (in both in- and out-directions)can be adjusted.

Fluidic flow through the essentially fluid-permeable material 100 can becontrolled by pressure difference generated across said material anevacuation pump provided in chemical deposition reactor and regulatingdevices, as described herein above.

When P_(in) exceeds P_(out), fluidic flow occurs from the interior side102 of the substrate holder 100 towards the reaction space 101. WhenP_(in) approximately equals to P_(out), fluid flow rate through thefluid-permeable wall (100) is close to diffusive. Thus, setting the flowrate for two distinct precursor fluids (viz. fluids containing distinctprecursor chemicals) flowing across the fluid-permeable wall in bothdirections (from “Out” to “In” and from “In” to “Out”) to very lowallows for obtaining distinct coatings 1 and 2 on the outer- and innersurfaces 10A, 10B, respectively. The flow rate regarded as very low isequal to or less than 10 sccm, preferably, equal to or less than 1 sccm,still preferably, equal to or less than 0.1 sccm. Sccm refers tostandard cubic centimeters per minute; cm³/min in standard conditionsfor temperature and pressure of the fluid, wherein said standardtemperature is 0 deg C. (273 K) and standard pressure is 1 atm).

Example 2. Deposition of the Interlaced Substrate 10 with a Coating

1a) Introduce inert carrier fluid X, such as nitrogen gas (N₂), into thereaction space 101 via the reaction chamber and, optionally, via thefeedline connected to the tubular substrate holder 100. Uponstabilization of the flow (0.1-100 s, prefereably, 1 s), add precursorA, such as titanium tetrachloride (TiCl₄), for example, to the“external” flow (delivered via the reaction chamber) carried by theinert carrier X. By adjusting pressure settings (hereby, P_(out)approximately equals P_(in)), the entire surface of the interlacedsubstrate (10A and 10B) shall be saturated with molecules A (FIG. 2 ,upper box).

1 b) Purge by directing inert fluid X into the reaction space via thereaction chamber and, optionally, via the feedline connected to thesubstrate holder 100. Purge duration 1-100 s, preferably, 10 s.

2b) Deliver a second precursor B, such as ammonia gas (NH₃) into thereaction space via the feedline connected to the tubular substrateholder 100, while directing the inert carrier X (N₂) into the reactionchamber. By adjusting the pressure such that P_(in) exceedsP_(out)(P_(in)>>P_(out)), precursor B is forced to penetrate through thefluid-permeable wall 100 and reside onto both surfaces 10A and 10B ofthe interlaced substrate 10. The precursor B enters chemical reactionwith precursor A thus forming a deposition layer AB, hereby, titaniumnitride (TiN), on both exterior- and interior surfaces 10A and 10B,respectively (FIG. 2 , lower box).

2b) Purge (same as 1a).

Repeat the deposition cycle (steps 1a, 1b, 2a and 2b) n times until thecoating of desired thickness is attained. The coating can comprise atleast one deposition layer AB or a “stack” of identical depositionlayers AB.

Example 3. Deposition of the Exterior- and Interior (10A, 10B) Surfacesof the Interlaced Substrate 10 with Coatings 1, 2 Having DistinctSurface Chemistry

1a) Same as step 1a in Example 2 (FIG. 3 , upper box). Conformaldeposition of the precursor A, hereby, TiCl₄, for example, onto theentire substrate 10 (surfaces 10A, 10B).

1b) Purge.

2a) Introduction of two different precursors B1 and B2. Deliver aprecursor chemical B1, such as ozone (O₃) or water vapor (H₂O) into thereaction space 101 via the reaction chamber and deliver anotherprecursor chemical B2, such as ammonia gas (NH₃) into the reaction spacevia the feedline connected to the tubular substrate holder 100. Bymaintaining P_(in) approximately equal to P_(out), different chemicalreactions A+B1 and A+B2 can be conducted at the outer-(10A) andinner-(10B) surfaces of the substrate 10, respectively. The procedureallows for producing a deposition layer AB1 (hereby, titanium oxide,TiO_(n)) on the exterior surface 10A along with producing a depositionlayer AB2 (hereby, titanium nitride, TiN) on the interior surface 10B ofthe substrate (FIG. 3 , lower box).

The precursors B1 and B2 can be delivered into the reactions spacesimultaneously or one by one. In the latter case, delivery of theprecursor fluid is accompanied by delivery of the carrier fluid X fromthe opposite side (not shown). For example, delivery of precursor B1into the reaction chamber is accompanied by guiding inert fluid Xthrough the substrate holder 100; whereas delivery of B2 into thereaction space 101 through the substrate holder 100 is accompanied byguiding inert fluid X into the reaction chamber.

2b) Purge.

3) Optional. Use any suitable precursor (e.g. B3, not shown), which isknown to react differently with B1 compared to B2, for selectivelycoating only one surface (10A or 10B) of the substrate.

Repeat the deposition cycle (steps 1a, 1b, 2a, 2b and, optionally, 3) ntimes until the coating of desired thickness is attained. By the method,homogenous coatings (AB1)_(n), (AB2)_(n) (n=a number of depositioncycles) of varying thickness can be deposited on any one of the surfaces10A, 10B, by “stacking” deposition layers AB1 on the outer surface 10A,while maintaining the flow of inert fluid through the interior 102 ofthe substrate holder 100 (or vice versa). Thus, the outer surface 10Acan be deposited with a 1 nm coating (1), whereas the inner surface—witha 0.5 nm coating (2), for example.

In fact, when the precursor B1 (O₃) enters chemical reaction withprecursor A (TiCl₄) on the outer surface 10A, an atomic layer oftitanium oxynitride (TiO_(x)N_(y)) can be formed on the outer surface10A. Thus, production of the coating 1 consisting of titanium (di)oxidemay require saturation of the reaction space 101 with ozone molecules ina number of subsequent pulses.

The procedure allows for production of coatings 1, 2 with differentsurface chemistries and/or rendered with different physical, chemicaland/or biological properties at each surface 10A, 10B. Each coating 1, 2thus comprises at least one deposition layer AB1, AB2.

Example 4. Production of Multilayer Coatings I

This example essentially combines the procedures disclosed in Examples 2and 3.

At first, the entire substrate 10 can be deposited with an at least onedeposition layer AB (e.g. TiN), in a manner shown on FIG. 2 (Example 2).Thereafter, the procedure according to the Example 3 (FIG. 3 ) can beapplied to establish at least one deposition layer AB1 (e.g. TiO₂) onthe outer substrate surface 10A or on the inner surface 10B.

Deposition series “AB (conformal, surfaces 10A, 10B)+AB1 (surface 10A)”and/or “AB+AB2 (surface 10B)” and/or “AB+AB1 and AB2” can be repeated ntimes as desired to produce heterogeneous coatings with uniformthickness across the substrate 10 or thickness varying for surfaces 10Aand 10B. In the example, the coating 1 (surface 10A) can comprisedeposition layers (AB)_(n) and (AB1)_(n), whereas the coating 2 (surface10B) can comprise deposition layers (AB)_(n) and (AB2)_(n).

Example 5. Production of Multilayer Coatings II

To obtain coatings 1, 2 with distinct composition (e.g. TiO₂ and TiN)from at least one common precursor, such as TiCl₄, for example, theprocedure can be further implemented as follows.

1a) Introduce inert carrier fluid X, such as nitrogen gas (N₂), into thereaction space 101 via the reaction chamber and, optionally, via thefeedline connected to the tubular substrate holder 100. Uponstabilization of the flow (0.1-100 s, preferably, 1 s) pulse a (common)precursor A (e.g. TiCl₄) into the reaction space 101 via the reactionchamber (not through the substrate holder), while preserving the flow ofinert carrier X through the substrate holder (P_(in) exceeds P_(out)).Due to the counterflow established by the inert carrier X through saidsubstrate holder, the precursor A (TiCl₄) cannot reach the inner surface10B of the substrate 10, which faces the fluid-permeable holder 100.

1b) Purge.

2a) Direct precursor B1 (e.g. H₂O) into the reaction space 101 via thereaction chamber (not through the substrate holder), while maintainingthe counterflow of inert carrier X through the substrate holder, wherebythe deposition layer AB1 (TiO₂) is generated on the outer surface 10A.The inner surface 10B remains uncoated.

2b) Purge.

3a) Conformal deposition of the precursor A (TiCl₄) onto the entiresubstrate (surfaces 10A, 10B). The common precursor (TiCl₄), is pulsedinto the reaction space 101 via the reaction chamber again; however,this time with no hindrance (counterflow) from the inside of thesubstrate holder 100 (P_(out) approximately equals P_(in)) thus enablingsaturation of the entire substrate surface with molecules A (in similarmanner as shown in Examples 2 and 3, steps 1a). It should be noted, thatin this case, the precursor A is deposited, at the outer surface 10A,onto the previously depositied layer AB1.

3b) Purge

4a) Deliver precursor B (e.g. HN₃) into the reaction space 101 via thereaction chamber in similar manner as for step 3a. In such a case,conformal growth of the deposition layer AB can be attained for theentire substrate.

Alternatively, delivery of the precursor B into the reaction space canbe optionally accompnied by re-establishing the inert counterflow (X)through the substrate holder 100. Inert counterflow can be establishedif growth of the deposition layer AB (TiN) is desired only for the outersurface 10A.

4b) Purge.

Procedure allows for conducting deposition series “AB1 (surface 10A)+AB(conformal, surfaces 10A, 10B)” and/or “AB1 (surface 10A)+AB (only forthe surface 10A)”. The latter option is obtainable in condition that thecounterflow is established from the interior 102 of the substrate holder100 at step 4a.

The deposition cycles 1-2 and 3-4 can be repeated n times. As result,the substrate 10 is rendered with surfaces 10A, 10B with differentproperties, attainable, in this Example, by regulating the inertcounterflow X from the interior 102 of the substrate holder 100.

Hence, in some embodiments, delivery of any one of the precursorchemicals into the reaction space 101 is accompanied by generating acounter flow of inert fluid in a direction essentially opposite to thedirection of delivery of precursor chemicals into the reaction space101.

The method further allows for selective deposition of coatings on one ofthe surfaces 10A or 10B, while deposition on the other surface can besustained or prevented.

In still another example, a hydrophobic precursor, such astridecafluoro-1,1,2,2-tetrahydrooctylmethyl-bis(dimethylamino)silane(also known as FOMB(DMA)S or C₈F₁₃H₄(CH₃)Si(N(CH₃)₂)₂), can be used asprecursor A to be deposited conformally on all surfaces of the substrate10, in a manner described hereinabove. After purge, any suitableprecursor B can be delivered into the reaction space 101 via thereaction chamber, while maintaining pressure difference across theinterior and exterior surfaces of the fluid-permeable substrate holder100 such, that said second precursor B does not penetrate inside thesubstrate holder (hereby, P_(in)>P_(out)) and reacts with precursor Aonly at the outer surface 10A. Region-specific coating can be attainedby establishing the inert counterflow through the substrate holder 100in a manner described hereinabove. Deposition cycles can be repeated ntimes until the coating (1, 2) with desired thickness is obtained. As aconsequence, only the inner surface 10B of the tubular substrate 10,such as stent, shall be deposited with the hydrophobic film.

In all embodiments, the precursor chemicals (e.g. A, B, B1, B2) aredelivered into the reaction space 101 in sequential, temporallyseparated pulses. In most instances, the reaction space is purged withinert fluid X after each precursor pulse. Inert fluid X can be guidedinto the reaction chamber via any feedline or feedlines including thefeedline(s) connected to the substrate holder 100.

In a latter case, purging of the fluid-permeable material occurs indirection from the interior 102 of the substrate holder towards thereaction space 101. Thus, once the reaction chamber is clear of gaseousreactants, it is still desired to purge the fluid-permeable substrateholder 100. Purging the substrate holder 100 generally requires moretime than purging the reaction space 101, due to slower penetration offluids through the fluid-permeable material. In such as case, purgingcan be a process, in where reverse flow of inert fluid (e.g. N₂) isestablished, thereupon fluid from the reaction space is sucked into thetube-shaped substrate holder through the porous walls. Purging saidtubular substrate holder can be faster, if the substrate holder isconfigured as a through-pipe. Reverse flow can be regulated by a valveprovided on an appropriate feedline (not shown).

For those skilled in the art it is clear that the precursors describedhereinabove to deposit the coatings 1, 2 (e.g. TiN, TiO_(n)) are mereexamples of compounds, which can be established, by ALD methods, from ametal-containing precursor (TiCl₄) and secondary chemicals, such asgases (NH₃, O₃/H₂O). Nevertheless, any compound suitable forestablishing a chemical reaction by ALD or CVD methods can be utilizedwithin the concept of the present invention.

Hence, the coatings 1, 2 can be established from a metal-containingprecursor (A) and at least two non-similar gaseous substances (B1, B2).In some other instances, the coatings 1, 2 can be established from anumber of metal-containing precursors. Utilization of various compounds(oxides, nitrides sulfides, etc.) that comprise elements other thanmetal, such as silicon dioxide, SiO₂, for example, is also not excluded.

Non-limiting examples for the coatings 1, 2 include aluminium oxide(Al₂O₃), zinc oxide (ZnO), or a combination thereof. These materials arebiocompatible and dissolve in controllable manner when in contact withbodily fluids, thus enabling production of implantable devices forcontrolled drug release.

In an aspect, a coated item 10 configured as an interlaced structure isprovided, said item comprises a first coating 1 on a first surface 10Aand a second coating 2 on a second surface 10B, wherein the firstcoating 1 and the second coating 2 differ from one another by virtue ofat least composition thereof. The coated item can be configured as animplantable device, such as a stent, e.g. a vascular stent, or acatheter.

In further aspect, an implantable medical device 10 is providedconfigured as an interlaced structure that comprises a first coating 1on a first surface 10A and a second coating 2 on a second surface 10B,wherein the first coating 1 and the second coating 2 differ from oneanother by virtue of at least composition thereof.

In embodiments, the coated implantable medical device 10 is a stent or acatheter.

It shall be appreciated by those skilled in the art that the embodimentsset forth in the present disclosure may be adapted and combined asdesired. The disclosure is thus intended to encompass any possiblemodifications of the deposition method, recognizable by those ofordinary skill in the art, within a scope of appended claims.

1. A coated item configured as an interlaced structure comprising acoating formed by a method comprising: obtaining a chemical depositionreactor with a reaction space formed by a reaction chamber andconfigured to receive, at least in part, a substrate holder made of afluid-permeable material, onto which an interlaced substrate is mountedsuch, that a first surface of the substrate faces the reaction space,and a second surface of the substrate is placed against the substrateholder, and in a number of deposition cycles, forming a first coating onthe first surface and/or forming a second coating on the second surface,wherein, each deposition cycle comprises delivering, with a flow offluid, a precursor chemical into the reaction space such, that deliveryof at least one precursor chemical into the reaction space occurs viasaid fluid-permeable material.
 2. The coated item of claim 1, comprisingthe coating formed by the method, wherein the substrate holder has anessentially hollow interior, into which said at least one precursorchemical is received.
 3. The coated item of claim 1, comprising thecoating formed by the method, wherein the deposition cycle comprisesdelivering at least two predetermined precursor chemicals into thereaction space, whereby a deposition layer is produced across the firstsurface of the substrate and/or across the second surface of saidsubstrate.
 4. The coated item of claim 1, comprising the coating formedby the method, in which a first predetermined precursor chemical isdelivered into the reaction space via the reaction chamber and a secondpredetermined precursor chemical, is delivered into the reaction spacevia the fluid-permeable substrate holder.
 5. The coated item of claim 1,comprising the coating formed by the method, in which the precursorchemicals are delivered into the reaction space in sequential,temporally separated pulses, optionally alternated by purging thereaction space with inert fluid.
 6. The coated item of claim 1,comprising the coating formed by the method, in which delivery of anyone of the precursor chemicals into the reaction space is accompanied bygenerating a counter flow of inert fluid in a direction essentiallyopposite to the direction of delivery of precursor chemicals into thereaction space.
 7. The coated item of claim 1, comprising the coatingformed by the method, wherein any one of the first coating and thesecond coating are formed by the at least one deposition layer depositedacross the first surface of the substrate and/or across the secondsurface of said substrate.
 8. The coated item of claim 1, comprising thecoating formed by the method, wherein the deposition layers forming thefirst coating differ from the deposition layers forming the secondcoating by virtue of at least composition thereof.
 9. The coated item ofclaim 1, comprising the coating formed by the method, wherein selectiveformation of the coating on the first surface and/or on the secondsurface is regulated by adjusting pressure of fluid flowing into thereaction space via the reaction chamber and/or via the fluid-permeablesubstrate holder.
 10. The coated item of claim 1, comprising the coatingformed by the method, wherein the substrate holder is made of afluid-permeable material selected from the group consisting of porousmetal, porous ceramics and porous polymer.
 11. The coated item of claim1, comprising the coating formed by the method, wherein the substrateholder is an essentially tubular structure.
 12. The coated item of claim1, configured as an essentially tubular interlaced structure formed by amesh or a web.
 13. The coated item of claim 1, configured as animplantable medical device, such as a stent or a catheter, or configuredto form a part of such device.
 14. The coated item of claim 1,comprising the coating deposited onto interlaced substrate with AtomicLayer Deposition (ALD).
 15. A coated implantable medical deviceconfigured as an interlaced structure, comprising a first coating on afirst surface and/or a second coating on a second surface, wherein thefirst coating and the second coating differ from one another by virtueof at least composition thereof.
 16. The coated implantable medicaldevice of claim 15, wherein the first surface is an exterior surface ofsaid device, and wherein the second surface is an interior surface,respectively.
 17. The coated implantable medical device of claim 15,configured as a stent or a catheter.